It's been stated before, but it bears repeating..

If you're going to have more than one kilt in a certain sett, nothing is more appropriate than your family tartan.

And...

For a tank (8 yard, 16oz, etc), you should (IMHO) go with (one of) your family tartan. Especially considering that you might be wearing it to clan functions. If you're a MacDonald, and you're at a MacDonald clan event, why would you wear a Black Watch? It would end up looking "rental-ish"